1. Field of the Invention
This invention relates to a sense amplifier circuit using thin film transistors.
2. Description of the Related Art
Recently, studies were conducted on thin film transistors which can be formed on an insulative substrate such as glass substrate. Such studies are disclosed in, for example U.S. Pat. Application Nos. 427,041, 427,252 and 467,736 which are filed by the same Applicant of this application. This type of memory can be used as an electrically erasable and programmable nonvolatile memory and has a feature that it can be easily manufactured in a large scale in comparison wit EEPROMs of floating gate type and MNOS type which are well known in the art.
When data is read out from the thin film transistor memory, it is necessary to amplify and discriminate a small analog signal by use of a sense amplifier circuit. However, in the prior art, a sense amplifier circuit formed of thin film transistors has been not realized. Therefore, when data is read out from the thin film transistor memory, it is necessary to use a sense amplifier circuit formed of bipolar transistors or MOS transistors. Since the conventional sense amplifier circuits cannot be formed on the glass substrate, it is required to use a high-level technique for connection between the thin film transistor memory formed on the glass substrate and the sense amplifier circuit.